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Long-awaited King County study recommends waste-to-energy site to replace landfill

Courtesy King County Solid Waste Division
The Cedar Hills Regional Landfill in Maple Valley is rapidly filling up.

King County is grappling with how to handle its trash as the Cedar Hills Regional Landfill reaches capacity. The Maple Valley facility, which first accepted waste in the mid-1960s, is expected to fill up in less than 20 years. Expansion efforts have stalled as neighbors complain about the effects of squeezing more refuse into the little space remaining.

A long-awaited study commissioned by the county looked at two alternatives. The conclusion after more than 300 pages of analysis is the recommendation to build a waste-to-energy facility that would incinerate trash and generate electricity.

The other option would be to ship the trash by rail to a landfill in Eastern Washington or Eastern Oregon. This would involve contracting with a train operator and constructing a new transfer and load facility.

The study compares the costs of the two options and finds them roughly equivalent in the short term, but says waste-to-energy would cost at least $4 billion dollars less over a 50-year time frame.

It also looked at carbon emissions and says although there are some technological hurdles, incineration has the potential to provide carbon-neutral electricity and even net negative emissions. This would require scrubbers as well as carbon capture and sequestration that has not yet been tested in the United States.

Council member Kathy Lambert, who has been studying the issue for more than a decade, welcomed the findings as the council voted to formally adopt the study. She said although this technology would be new in the region, there's a waste-to energy facility in Hamburg, Germany that is a model for all of the European Union.

“The rest of the world is doing this. There’s data online 24/7 out of Hamburg, so that we can see exactly what’s happening,” Lambert said.

Among the unknowns is exactly how such a plant would offset its carbon emissions and how it would sequester carbon dioxide. The report also points out that as a local electricity producer, the new facility would have to comply with the new state law requiring all local electricity to be carbon neutral by the year 2030.

The study estimates it could take eight to 10 years to find a site and build a waste-to-energy facility and recommends the county begin work on it now. One estimate shows space at Cedar Hills could run out as early as 2025, though the study says simply “by 2040.”

The King County Council has formally accepted the report and can use it as a foundation for legislation as it takes next steps.

The regional landfill serves all of unincorporated King County, as well as 37 of its 39 cities.  

Bellamy Pailthorp covers the environment beat for KNKX, where she has worked since 1999. From 2000-2012, she covered the business and labor beat. Bellamy has a deep interest in Indigenous affairs and the Salish Sea. She has a masters in journalism from Columbia University.